WD Purple 3TB Surveillance Hard Disk Drive -5400 RPM Class SATA 6Gb/s 64MB Cache 3.5 Inch Model WD30PURX Brand WD, Series Purple, Model WD30PURX Capacity 3TB, Packaging Bare Drive, Interface SATA 6.0Gb/s, RPM 5400 RPM, Cache 64MB, Usage For Video Surveillance, Form Factor 3.5", Height (maximum) 26.10mm, Width (maximum) 101.60mm, Length (maximum) 147.00mm,